Header assembly for lasers

ABSTRACT

A header assembly includes a header and a connector both formed from an electrically and thermally conductive material. One or more light emitting members are mounted on the header and are connected between the header and the connector. In use, pluralities of aligned header assemblies are mounted adjacent each other to form sets of header assemblies. The sets are in turn positioned around a laser rod with the light emitting members of the header assemblies facing the rod.

United States Patent [1 1 Kay Nov. 6, 1973 HEADER ASSEMBLY FOR LASERS3,351,698 11/1967 Marinace 317/235 3,438,057 4/1969 Neitzel 313/108 D[75] Inventor- Dav'd 3,471,801 10/1969 Woodbury et al..... 331/94 5 73 iTexas Instruments lncoporated, 3,519,888 7/1970 Parrish 317/234 1 DallasTeX 3,581,162 5/1971 Wheatley 317/234 [22] Filed: 1973 PrimaryExaminer-John W. Huckert [21] App]. No.: 337,815 AssistantExaminerAndrew J, James Related us. Application Data Randy [63]Continuation of Ser. No. 880,877, Nov. 28, 1969,

abandoned. [57] ABSTRACT A header assembly includes a header and aconnector 52 17 A l 1 U 5 3 4 both formed from an electrically andthermally con- [511 Int Cl i 11/00 15/60 ductive material. One or morelight emitting members [58] Field 313/1083), 317/234 are mounted on theheader and are connected between 4 235 331/945 the header and theconnector. In use, pluralities of aligned header assemblies are mountedadjacent each [56] References Cited other to form sets of headerassemblies. The sets are in turn positioned around a laser rod with thelight emit- UNITED STATES PATENTS ting members of the header assembliesfacing the rod. 2,669,663 2/1954 Pankore 317/235 3,303,432 2/1967Garfinkel 313/108 D 9 Claims, 8 Drawing Figures lll PATENTEDnnv 5 ms3.771; 031

SHEET 1 BF 2 INVENTOR: DAVID B. KAY

r ATTORNEY HNVENTOR: I DAVID B. KAY

ATTORNEY PATENTED NOV 6 I975 SHEET 2 BF 2 FIG. 7

HEADER ASSEMBLY FOR LASERS This is a continuation of application Ser.No. 880,877, filed Nov. 28, 1969 and now abandoned.

At the present time, a number of different lasers are known and in use.These include crystalline lasers, liquid lasers, glass lasers, gaslasers and semiconductor lasers. This invention relates to lasers thatare excited by light emitting diodes. Lasers of this type have certainadvantages over other lasers in that they include solid state componentsand are therefore relatively uncomplicated to design, construct andoperate.

' In particular, the present invention relates to header assemblies forlight emitting members. In accordance with the preferred embodiment, aheader assembly includes at least one light emitting member and a headerthat both supplies an electric potential to and removes heat from thelight emitting member. The assembly further includes a connector that iselectrically connected to the light emitting member.

In the practice of the invention, groups of individual header assembliesare joined into sets. The sets of header assemblies are in turnpositioned around a laser rod to form a laser. In this manner, a laserincluding any desired number of light emitting members is easilyfabricated.

A more complete understanding of the invention may be had by referringto the following detailed description when taken in conjunction with thedrawings, wherein:

FIG. I is a prespective view ofa header assembly employing theinvention;

FIG. 2 is a prespective view of a set of header assemblies;

FIG. 3 is an end view of a laser including sets of header assemblies;

FIG. 4 is an end view of another laser including sets of headerassemblies;

FIG. 5 is a prespective view of another header assembly employing theinvention;

FIG. 6 is a prespective view of still another header assembly employingthe invention;

. FIG. 7 is, an illustration of an alternative embodiment of theinvention, and

FIG. 8 is an illustration of another alternative embodiment of theinvention.

Referring now to the drawings, and particularly to FIG. 1, a headerassembly 10 employing the invention is shown. The assembly 10 includes aheader 12 which comprises a plate shaped body formed from anelectrically and thermally conductive material such as copper, silver,molybdenum, etc. The header 12 includes an end surface 14 and a pair ofangularly extending header locating surfaces 16. A light emitting member18 is mounted on the surface 14 of the header 12.

The light emitting member 18 includes a submount 20 positioned inengagement with the surface 14 of the header I2 and a light emittingdiode 22 positioned on the upper surface of the submount 20. Thesubmount 20 comprises a body of conductive silicon or the like and has anon-conductive oxide layer formed on a portion of its upper surface. Thediode 22 has two terminals, one of which engages the conductive body ofthe submount 20 and is therefore connected to the header I2 and theother of which is connected to a printed circuit lead 24 formed on theoxide layer of the submount 20.

The assembly 10 further includes a connector 26 which also comprises aplate shaped body of electrically and thermally conductive material. Theconnector 26 is positioned adjacent the header 12 and includes a pair oflocating surfaces 28 which extend at the same angle as the surfaces 16of the header 12 The connector 26 is connected to the diode 22 of thelight emitting member 18 by a lead 30 which extends to the printedcircuit lead 24 formed on the submount 20. The top of connector 26 mayextend above end surface 14 for protection of the diode 22 as well as tofacilitate electrical interconnection thereto. Furthermore the topportion of connector 26 extending; above the surface 14 may bereflective to enhance optical coupling.

The header 12 and the connector 26 are separated by a layer. ofelectrically insulating material 32. Another layer of electricallyinsulating material 34 is formed either on the outside surface of theheader 12 as shown, or on the outside surface of the connector 26. Amounting hole 36 extends through the several components of the headerassembly 10. The hole 36 includes a reduced diameter portion formed inthe header 12 and an enlarged diameter portion formed in the connector26.

Referring now to FIG. 2, a set of header assemblies 40 including aplurality of identical header assemblies 10 is shown. The assemblies 10comprising the set 40 are positioned adjacent each other along a lineand are insulated from each other by their respective layers ofelectrically insulating material 34. The assemblies 10 are retained inthe set 40 by a bolt 42 which extends through the holes 36 formedthrough the assemblies. The bolt 42 is comprised of a thermallyconductive material and has a coolant passageway 44 formed through it.The outside diameter of the bolt 42 is equal to the inside diameter ofthe reduced diameter portions of the holes 36 and, accordingly, the bolt42 engages the headers 12 of the set 40 but does not engage theconnectors 26 thereof. Although the. transfer of heat requirement hasbeen illustrated by utilizing coolant passageway 44 (and passing acoolant therethrough), it will be recognized that the bottom portion ofheader 12 may be extended and flared to form a fin for connection,radiation or forced air cooling.

A laser 50 employing three sets of header assemblies 40 is shown in FIG.3. In the laser 50, the sets of header assemblies 40 are positioned inan array around a laser rod 52. The sets 40 are separated by spacermembers 54 having reflective surfaces 56, it being understood that asused herein the term reflective is not limited to mirror surfaces andincludes white and other similarly reflective surfaces. The members 54also include locating surfaces 58 which cooperate with the surfaces 16of the headers 12 and the surfaces 28 of the connectors 26 to form anarray that encloses the laser rod 52. The members 54 either are formedfrom an electrically insulating material or are electrically insulatedfrom the assemblies 10.

In the use of the laser 50, the diodes 22 of the header assemblies 10are energized by connecting the headers 12 and the connectors 26 of theassemblies to suitable sources of electrical potential. This may beaccomplished either on an individual assembly basis or by forming eitherparallel or series connections to each connector 26 and to each header12 comprising a set 40. Upon energization, the diodes 22 excite or pumpthe laser 50 by producing light that is converted by the laser rod 52into a laser beam. During this operation, heat is removed from thediodes 22 by passing a coolant through the passageways 44 formed in thebolts 42 of the sets 40.

By way of example, assume that the laser rod 52 is formed from thematerial known as neodymium in the yttrium aluminum garnet (NdzYAG). Insuch a case, the diodes 22 are preferably similar in construction to thetype sold by Texas Instruments, Incorporated as a part of the productidentified as TIXLO9 but are preferably comprised of gallium arsenidephosphide. Diodes of this type can be made to produce light having anominal wave length of 8,000 angstroms and having a band width of about200 angstroms. Such light is converted by the NdzYAG rod into a laseroutput.

A laser 60 employing five sets of header assemblies 40 is shown in FIG.4. The laser 60 is similar to that laser 50 in that it includes a laserrod 62 that is excited by the diodes 22 of the assemblies 10. The laser60 differs from the laser 50 in that it is comprised entirely of sets ofheader assemblies 40 and in that the surfaces 14 of the headerassemblies 10 are reflective. In the laser 60, the surfaces 16 and 28 ofthe assemblies 10 are mounted in engagement with but insulated from eachother so that the laser rod 62 of the laser 60 is completely enclosed.

Referring now to FIG. 5, a modified header assembly 66 is shown. Themodified assembly 66 is similar to the assembly 10 shown in FIG. 1except that the surface 14 of the modified assembly 66 is positionedbetween a pair of upstanding projections 68. The projections 68 includeinterior surfaces 70 which are made reflective in order to concentratethe light emitted from the diodes 22. The projections 68 also protectthe light emitting member 18 in case the modified assembly 66 isdropped, etc. Similar to FIG. 1, electrical connection to the headerassembly in FIG. is made through tabs 71.

A second modified header assembly 72 is shown in FIG. 6. The assembly 72differs from the assembly shown in FIG. 1 principally in that it has apair of holes 74 and 76 formed through it. The hole 74 is a mountinghole and serves the same function as the hole 36 of the assembly 10. Thehole 76, on the other hand, comprises a coolant passageway. In the useof the assembly 72, the layers of insulation 32 and 34 serve as gasketsto prevent the leakage of coolant flowing in the passageway 76.

Referring now to FIG. 7, a header assembly 80 comprising a secondembodiment of the invention is shown. The assembly 80 is similar to theassembly 10 in that it includes a header 82 and a connector 84, both ofwhich are formed from an electrically and thermally conductive material.The header 82 has an end surface 86 and locating surfaces 88 and theconnector 84 has locating surfaces 90.

The assembly 80 differs from the assembly 10 primarily in that thesurface 86 of the header 82 supports four light emitting members 92.Each of the members 92 includes a submount 94 formed from an insulatingmaterial and a light emitting diode 96. The diode 96 of the members 92have two terminals which are connected to printed circuit leads 98formed on the submounts 94. I

The four lights emitting members 92 of the header assembly 80 areconnected in series with each other and with the header 82 and theconnector 84 of the as sembly by a plurality ofleads 100. One of theleads 100 extends from the header 82 to a printed circuit lead 98 on oneof the members 92. Another lead 100 couples the connector 94 to aprinted circuit lead 98 on another member 92. The remaining leads 100extend between printed circuit leads 98 on adjacent members 92 toconnect the members in series.

In the use of the second embodiment, a plurality of identical headerassemblies are joined into a set similar to the set 40. Then, one ormore sets are employed in a laser, such as the laser 50 or the laser 60.The resulting laser is operated identically to the laser 50 except thatthe individual header assemblies 80 comprising the laser produce morelight than the individual assemblies 10 comprising the laser 50.

FIG. 8 comprises an illustration of the third embodiment of theinvention. The third emboidment comprises a header assembly 102 which issimilar to the assembly 80 in that it includes four light emittingdiodes 104. However, the diodes 104 of thethird embodiment are mountedon a single submount 106 formed from an insulating material. Thesubmount 106 includes a plurality of printed circuit leads 108 wouldconnect the various light emitting diodes 104 of the third embodiment inseries. One of the leads 108 is connected to the connector of theassembly 102 by a wire 110. Another of the leads 108 is connected to theheader of the assembly 102 by a wire 112. The third embodiment of theinvention is operated identically to the second embodiment.

It should be understood that although the embodiments and modificationsof the invention shown in the drawings are preferred, the invention iscapable of numerous variations. For example, each header assembly cansupport any convenient number of light emitting members. The lightemitting members of each assembly can be connected either in series orin parallel. The light emitting members of the various assembliescomprising a set need not be of the same type and can vary in number.And, the header assemblies can be of any desired shape and can bearranged in any conveneint manner.

The use of the present invention results in several advantages over theprior art. First, extremely high diode packing densities are achieved.Second, header assemblies constructed in accordance with the inventioncomprise building blocks that can be employed to mount any desirednumber of light emitting members in a laser, including very largenumbers of diodes. Third, the use of the invention results in a minimumnumber of non-reflective surfaces and in maximum heat transfer from thelight emitting members and is, therefore, consistent with the opticaland temperature requirements of lasers. Fourth, the invention permitsthe wiring of light'emitting members individually, in series or inparallel, as desired. Fourth, the use of individual header assembliessimplifies laser construction and repair.

Although specific embodiments of the invention are illustrated in thedrawings and described herein, it will be understood that the inventionis not limited to the embodiments disclosed but is capable ofrearrangement modification and substitution of parts and elementswithout departing from the spirit of the invention.

What is claimed is:

1. A header assembly for optically pumping laser rods comprising incombination:

a. a header formed from a thermally and electrically conductivematerial, said header having at least two angularly extending headerlocating surfaces and at least two substantially parallel sides;

b. a connector formed from an electrically conductive material, saidconnector having at least two substantially parallel sides;

0. means for positioning said connector in substantially parallelrelationship to and electrically insulated from said header;

d. at least one light emitting member mounted on said header; and

e. connecting means for connecting said light emitting member to saidheader and to said connector.

2. A header assembly in accordance with claim 1 wherein said lightemitting member includes a light emitting diode.

3. A header assembly in accordance with claim 1 wherein said lightemitting-member includes a plurality of light emitting diodes.

4. A header assembly in accordance with claim 1 wherein said lightemitting member includes a plurality of light emitting diodes with eachof said diodes positioned on an individual submount, each submount beingsecured to said header.

5. A header assembly for a laser using a laser rod comprising:

a. a header including a thermally and electrically conductive bodyhaving a tetrahedrally shaped end surface, first opposing sides havingportions depending outwardly from said end surface to form headerlocating surfaces, and second opposing sub stantially parallel sidesdepending from said end surface;

b. layers of insulating material attached to the depending substantiallyparallel sides of the thermally and electrically conductive body forelectrically insulating said pair of parallel sides;

c. an electrical connector attached to the insulating layer of one ofsaid parallel sides, said electrical connector having an end terminatingadjacent to the end surface of said thermally and electricallyconductive body;

d. at least one light emitting means operatively attached to the endsurface of said body; and

e. coupling means electrically coupling the at least one light emittingmember to the electrical connector; whereby a plurality of said headerassemblies may be positioned with their parallel sides successivelyadjacent to one another to form a linear set of header assemblies and aplurality of sets positioned with locating surfaces abutting adjacentlocating surfaces for forming a tubular array for the laser rod.

6. A header assembly according to claim 5 wherein said header assemblyincludes a passage through said substantially parallel surfaces,insulating layers, and:

connector for a coolant for removing heat from said header.

7. A header assembly according to claim 5 wherein said header includes afin formed onthe lower surface thereof.

8. A header assembly according to claim 5 wherein said light emittingmeans includes a submount positioned on the thermally and electricallyconductive body of said header, said submount having a portion thereofin electrical contact with said thermally and electrically conductivebody and an insulating portion bearing an electrical lead insulated fromsaid thermally and electrically conductive body, a light emitting diodepositioned on said submount with electrical contacts connectedrespectively to the portion in electrical contact with the thermally andelectrically conductive body and electrical lead of said submount; andmeans electrically coupling said submount lead to said connector.

9. A header assembly according to claim 5 wherein the outwardlydepending portion of said opposing sides of said thermally andelectrically conductive body extend above said tetrahedrally shaped endsurface and include reflective interior surfaces for reflecting lightupwardly for improving the light output of the header assembly.

1. A header assembly for optically pumping laser rods comprising incombination: a. a header formed from a thermally and electricallyconductive material, said header having at least two angularly extendingheader locating surfaces and at least two substantially parallel sides;b. a connector formed from an electrically conductive material, saidconnector having at least two substantially parallel sides; c. means forpositioning said connector in substantially parallel relationship to andelectrically insulated from said header; d. at least one light emittingmember mounted on said header; and e. connecting means for connectingsaid light emitting member to said header and to said connector.
 2. Aheader assembly in accordance with claim 1 wherein said light emittingmember includes a light emitting diode.
 3. A header assembly inaccordance with claim 1 wherein said light emitting member includes aplurality of light emitting diodes.
 4. A header assembly in accordancewith claim 1 wherein said light emitting member includes a plurality oflight emitting diodes with each of said diodes positioned on anindividual submount, each submount being secured to said header.
 5. Aheader assembly for a laser using a laser rod comprising: a. a headerincluding a thermally and electrically conductive body having atetrahedrally shaped end surface, first opposing sides Having portionsdepending outwardly from said end surface to form header locatingsurfaces, and second opposing substantially parallel sides dependingfrom said end surface; b. layers of insulating material attached to thedepending substantially parallel sides of the thermally and electricallyconductive body for electrically insulating said pair of parallel sides;c. an electrical connector attached to the insulating layer of one ofsaid parallel sides, said electrical connector having an end terminatingadjacent to the end surface of said thermally and electricallyconductive body; d. at least one light emitting means operativelyattached to the end surface of said body; and e. coupling meanselectrically coupling the at least one light emitting member to theelectrical connector; whereby a plurality of said header assemblies maybe positioned with their parallel sides successively adjacent to oneanother to form a linear set of header assemblies and a plurality ofsets positioned with locating surfaces abutting adjacent locatingsurfaces for forming a tubular array for the laser rod.
 6. A headerassembly according to claim 5 wherein said header assembly includes apassage through said substantially parallel surfaces, insulating layers,and connector for a coolant for removing heat from said header.
 7. Aheader assembly according to claim 5 wherein said header includes a finformed on the lower surface thereof.
 8. A header assembly according toclaim 5 wherein said light emitting means includes a submount positionedon the thermally and electrically conductive body of said header, saidsubmount having a portion thereof in electrical contact with saidthermally and electrically conductive body and an insulating portionbearing an electrical lead insulated from said thermally andelectrically conductive body, a light emitting diode positioned on saidsubmount with electrical contacts connected respectively to the portionin electrical contact with the thermally and electrically conductivebody and electrical lead of said submount; and means electricallycoupling said submount lead to said connector.
 9. A header assemblyaccording to claim 5 wherein the outwardly depending portion of saidopposing sides of said thermally and electrically conductive body extendabove said tetrahedrally shaped end surface and include reflectiveinterior surfaces for reflecting light upwardly for improving the lightoutput of the header assembly.